Table 2: Effect of patient characteristics on rate of blood pressure screening
CharacteristicBivariateMultivariate
RR (95% CI)p valueRR (95% CI)value
No. of recorded encounters1.03 (1.02-1.04)< 0.00011.03 (1.02-1.04)< 0.0001
Age at first encounter1.06 (1.03-1.08)< 0.00011.06 (1.03-1.10)0.0002
Female sex1.18 (1.10-1.28)< 0.00011.12 (1.03-1.20)0.01
Mean BMI centile1.11 (0.91-1.36)0.3--
Obesity*1.07 (0.88-1.31)0.5--
Recorded family history of hypertension1.44 (1.02-2.05)0.041.26 (0.81-1.95)0.3

Note: BMI = body mass index, CI = confidence interval, RR = rate ratio. Poisson regression used to model the rate of BP screening: number of recorded BP was used as outcome, age period (duration) was used as offset. The correlation between observations in the same cluster is approximately 0.36 - therefore Generalized Estimation Equation (GEE) was used to account for clustering of outcomes within physicians. Only variables with p value < 0.05 in bivariate model were included in multivariate model (i.e., no. of recorded encouters, age at first encounter, female sex, recorded family history of hypertension).

*BMI centile > 95%.